The present disclosure relates to the subject matter contained in Japanese Patent Application No. 2002-166512 filed on Jun. 7, 2002, which is incorporated herein by reference in its entirety.
1. Field of the Invention
This invention relates to an image display apparatus and more particularly to an image display apparatus which is adopted for a navigation system and uses real image data corresponding to an image such as a satellite photograph or an aerial photograph of the earth""s surface.
2. Description of the Related Art
A navigation system in a related art can display a map on a screen of a display based on road map data recorded on a DVD-ROM, etc., and further can display the current position on the map and guide the user through the route to the destination based on the position data of the navigation system.
However, since the navigation system in the related art uses the map data to prepare the displayed map image, it is difficult for the user to understand the current position through the map image and grasp the actual circumstances surrounding the current position; this is a problem.
This problem is caused by the fact that the map image is hard to represent the up and down positional relationship of overpass and underpass roads, etc., and that, in fact, a large number of roads, buildings, etc., are not displayed on the map image.
As one of means for solving such a problem, an art of displaying the current position on an aerial photograph image prepared from aerial photograph data is disclosed (JP-A-5-113343). To use the aerial photograph image, a building, etc., as a landmark becomes very easy to understand, thus making it possible for the user to easily understand the current position and also easily grasp the actual circumstances surrounding the current position.
However, the aerial photograph image prepared using aerial photograph data does not always make it possible for the user to more easily understand the current position and more easily grasp the actual circumstances surrounding the current position than the map image prepared using map data; the map image may make it possible for the user to more easily understand the current position than the aerial photograph image.
Therefore, it seems that a navigation system using both an aerial photograph image and a map image rather than a navigation system using only an aerial photograph image or a navigation system using only a map image will be mainstream as a next-generation navigation system. Thus, in the future, it will become important to properly use a real image such as an aerial photograph image and a map image having different features.
It is therefore an object of the invention to provide an image display apparatus which is adopted particularly for a navigation system and can properly use both a real image such as an aerial photograph image and a map image prepared using map data to enhance the user satisfaction.
To the end, according to the invention, according to a first aspect of the invention, an image display apparatus includes a display screen and a display control unit. The display control unit displays a map image and a real image on the display screen on the same scale concerning the same region based on map data and real image data. The display control unit displays one of the map image and the real image as a background. The display control unit combines the map image and the real image in a predetermined region so that only the other is displayed in the predetermined region.
In the first aspect, the one of the map image and the real image (for example, satellite photograph, aerial photograph, etc.,) is displayed as the background and the other is superposed thereon in the predetermined area on the same scale. Furthermore, the images are combined so that only the other is seen in the predetermined region.
For example, when the map image is displayed as the background, in the predetermined area, the composite coefficient of the map image is set to 0 and that of the real image is set to 1 for combining the images, so that only the real image is seen in the predetermined area. Consequently, only the real image is incorporated into a part of the map image, which is displayed as the background on the display screen, so that it is made possible to capture a target, etc., from many other angles.
According to a second aspect of the invention, an image display apparatus includes a display screen and a display control unit which displays a map image and a real image, which have the same scale and show the same area, on the display screen on the basis of map data and real image data. The display control unit displays one of the map image and the real image as a background, combines the map image and the real image in a predetermined region so that the other is seen through the one in at least a part of the predetermined region, and displays the combined image in the predetermined region.
In the second aspect, the one of the map image and the real image. (for example, satellite photograph, aerial photograph, etc.,) is displayed as the background, and the other is superposed in the predetermined area on the same scale. For example, when the map image is displayed as the background, the real image is superposed on a part of the map image, so that it is made possible to capture a target, etc., from many other angles.
Further, in the second aspect, for at least a part of the predetermined region in which the images are superposed on each other, the images are combined so that from under the one of the images, the other becomes transparent.
For example, when the map image is displayed as the background, in the predetermined region, the composite coefficient of the map image is set to xcex1 (0xe2x89xa6xcex1 less than 1) and that of the real image is set to xcex2 (=1xe2x88x92xcex1) for combining the images, and the map image becomes transparent from under (all or a part of) the real image in the predetermined region. Thus, a very large number of pieces of information can be provided for the user.
According to a third aspect of the invention, in the first aspect, the image display apparatus further includes a composite degree setting unit which sets a composite degree of the map image and the real image. The display control unit combines the map image and the real image on the basis of the composite degree.
In the third aspect, the composite degree can be set, so that the user can make adjustment so as to raise the display luminance of the map image (lower the display luminance of the real image) or raise the display luminance of the real image (lower the display luminance of the map image) in the predetermined region in which the images are superposed as desired. Therefore, a display state responsive to the user""s preference can be realized.
According to a fourth aspect of the invention, in any one of the second and third aspects, the display control unit combines the map image and the real image so that luminance value of the combined image increases as approaching to a boundary of the predetermined region.
In the fourth aspect, the images are combined so as to raise the display luminance of the background image as approaching the outside of the superposition area from the superposition region, so that image transition from the superposition region to the outside of the superposition region can be made smooth.
According to a fifth aspect of the invention, a navigation apparatus provide a user with information required reaching a destination to guide the user to the destination. The navigation apparatus includes a display screen and an image display device. The image display device includes a display screen and a display control unit which displays a map image and a real image, which have the same scale and show the same area, on the display screen on the basis of map data and real image data. The display control unit displays one of the map image and the real image as a background. The display control unit combines the map image and the real image in a predetermined region so that the other is seen through the one in at least a part of the predetermined region. The display control unit displays the combined image in the predetermined region.
According to a sixth aspect of the invention, in the fifth aspect, the predetermined region is one of a peripheral region of a current position of a vehicle obtained on the basis of current position information, a peripheral region of a predetermined facility obtained on the basis of predetermined facility position information, and a peripheral region of a predetermined position obtained on the basis of predetermined position information specified by the user.
In the sixth aspect, the predetermined area is any of the region surrounding the current position, the region surrounding the destination, the region surrounding the predetermined facility (for example, a station), or the region surrounding the predetermined position previously specified by the user (for example, home position). Thus, for example, when the map image is displayed as the background, the real image is displayed in the region.
Therefore, an image having different quality from the background image is displayed in the attention region, so that the attention region and any other portion can be discriminated from each other.
According to a seventh aspect of the invention, in the fifth aspect, the predetermined region is one of an upper half of the display screen and a lower half of the display screen.
In the seventh aspect, the predetermined area is the approximately upper half area or the approximately lower half area of the display screen. Therefore, the map image can be displayed in the approximately upper half area and the real image can be displayed in the approximately lower half area or the real image can be displayed in the approximately upper half area and the map image can be displayed in the approximately lower half area.
In the navigation system, often the area surrounding the current position is displayed in the lower portion of the display screen and a location at a large distance from the current position is displayed in the upper portion of the display screen. Thus, in the seventh aspect, an image on a nearby side and an image on a distant side can be discriminated from each other with the current position as the reference.
According to an eighth aspect of the invention, in the fifth aspect, the predetermined region is a peripheral region of a route for the destination obtained on the basis of route information.
In the eighth aspect, the predetermined region is the region surrounding the route. Thus, for example, when the map image is displayed as the background, the real image is displayed in the region surrounding the route.
Therefore, an image having different quality from the background image is displayed in the region surrounding the route, so that the region surrounding the route and any other portion can be discriminated from each other.